Comparison and Analysis of Same-Day Repeated Swept-Source Optical Coherence Tomography Biometry Scans

BACKGROUND: To evaluate the effectiveness of same-day repeated scans using a swept-source optical coherence tomography (SS-OCT) biometer (IOLMaster 700) when the initial scan resulted in a "warning" and/or "failed" variable.

METHODS: This is a retrospective observational cohort study at a tertiary care academic referral center. Among 5619 SS-OCT biometer scans reviewed between 2017 and 2021, 2293 met the inclusion criteria with 1167 same-day rescans. Each scan's variables received a "successful," "warning," or "failed" result across nine biometric parameters: axial length, anterior chamber depth, central corneal thickness, keratometry, lens thickness, posterior keratometry, total keratometry, white-to-white distance, and aqueous depth. Scans achieving "successful" results for all nine variables were deemed "perfect scans." Warning and failed results were analyzed separately for per-parameter analyses given their differing clinical implications for IOL power calculation.

RESULTS: After excluding perfect initial scans, among 909 suspect sessions, only 361 (38.1%) rescans yielded better results, while 587 (61.9%) demonstrated an identical or worse outcome (95% CI: 59-65%, p < 0.001). When analyzing all nine variables across all rescans, the subsequent scan showed an identical or worse outcome in 804 (68.9%) cases (95% CI: 66-72%, p < 0.001). In rescans where the initial scan received a "warning" or "failed" result for any individual variable, 35.8-56.0% improved depending on the parameter. Among improved scans, mean absolute differences were minimal, suggesting limited clinical significance.

CONCLUSIONS: Repeat scans improve the quality of biometric measurements in eyes showing warning or failed results from the studied SS-OCT biometer in fewer than half of cases for most parameters.